In crime scene investigations there is a lot of evidence that is valuable. That is including hair that is found at a crime scene. However, hair may not be seen as valuable evidence, but it is. Hair can tell you things that other evidence cannot. It can give you information about the unknown perpetrator and narrow your list of suspects. Hair is the most common type of trace evidence. Hair is easily transferred and resilient. Therefore, making it the most probable to be found at a crime scene during the investigation. It does not matter whether the hair was extrapolated or fell out.
It is more than likely going to be found during investigation. However, even if the perpetrator took extra precaution and got rid of all evidence, they wouldn’t stop to think to get the hair off the victim. Normally because they are on the run and do not have time to waste. If hair is found at a crime scene, the hair could allow you to unlock different mysteries about the perpetrator. For instance, you can learn the race of the person by inspecting the hair under a microscope. You will also be able to learn the hair color of the victim.
This allows you to narrow your list of suspects even more. If the victim pulled out the hair from the perpetrator then you will be able to find nuclear DNA (nDNA) off of the follicle. This type of DNA can create a DNA unique to the hair’s owner. If the hair happened to fall out, then you would be able to find mitochondrial DNA (mtDNA). This type of DNA can narrow it down to the mother’s side of the family. Mitochondrial DNA does not require the follicle to be on the hair because mtDNA is found along the shaft of the hair.
Toxicology of hair can tell you if a person did drugs or if the person happened to be poisoned by the perpetrator. If the hair contained any chemicals or was dyed Forensic Scientists would be able to tell. Furthermore, hair can give a prospect of the perpetrators cultural reference, because when looking at hair you can determine the types of foods they have eaten. In addition, both public and private forensic science laboratories offer services of hair comparisons as to which have been used in many testimonies in local, state, and federal courts for decades.
That is because it meets all the criteria required by the Federal Rules of Evidence, Frye, and Daubert. Empirical testing demonstrates that, while not absolute positive identification, hair comparisons are good evidence of association (2004). Additionally, there are multiple scientific studies that support the importance of hair. For example, one study conducted by Strauss in 1983 used 100 individuals comprising 54 Caucasians, 19 Negroid, and 27 Mongoloid. Seven hairs were chosen to represent the widest variety possible out of the 100.
These were designated as known slides after they were put onto glass microscope slides. Designated as questioned samples were the hairs chosen from the 100 samples and put onto glass microscope slides. They then used a checklist and punch cards to individually characterize all 800 hairs (700 known hairs and 100 questioned hairs). A series of seven experiments were conducted. 10 single questioned hairs to be compared with 10 known samples were selected by a neutral party. This experiment resulted in 100 percent accuracy. This showed that they could reliably associate a questioned hair with a known hair.
Furthermore, the study showed that the examiners accurately identified each of the 100 individuals in the questioned hair pool to the correct known hair group. In 1974 a similar experiment was conducted by Gaudette and Keeping. Gaudette and Keepings obtained head-hair samples from 100 individuals. 92 were Caucasian, 6 were Mongoloid, and 2 were Negroid. 6 to 11 macroscopically dissimilar hairs were selected. These were used to represent the range of microscopic characteristics in the known samples. Just as Strauss used punch cards to categorize the hairs, so did Gaudette and Keeping.
The cards from each individual were combined with all the others and were sorted based on if they had similar holes within the punch card. The hairs that had similar punch cards were then examined and compared under a microscope. A total of 370,230 comparisons were made out of the total 861 hairs from the 100 different individuals. Only 9 pairs of hair were determined undistinguishable. Gaudette later then conducted another experiment. This time however, he obtained 30 pubic hairs from 60 different individuals.
All of which were Caucasian hairs. to 11 dissimilar hairs were randomly picked from these to represent the range of characteristics presented in the 30 hairs. These characteristics were coded on punch cards, then combined and sorted. 102,831 comparisons were made from the 454 hairs. Only 16 from this study were found to be undistinguishable. Gaudette later stated in 1978 that “the significance of this research is not in the actual probability numbers found, but in experimental proof of the proposition that macroscopic and microscopic hair comparison is a useful technique and that hair evidence is good evidence”.
However, if there is an association between two people or a person and an object based on hairs recovered for evidentiary items it would be determined by microscopic hair comparisons, which has been used for the past century. The scientific community and legal community have both accepted these comparisons for the past 75 years and continue to accept them. On the other hand, since hair is not a means of personal identification, this information must be conveyed both in a written report and during testimony.
Although, these studies mentioned above do show that the method is reliable and repeatable. A mass amount of information can be gathered from the microscopic analysis and comparison of hairs. This information can be crucial to a case, such as the ability to exclude suspects who are not the source of an evidence hair. Hair is not only valuable, but it is also reliable as shown with the multiple studies presented above. Hair is the only evidence that remains after all bodily evidence disappears.
However, hair should not be used alone in a case, but it should be used to support other evidence. As Kathy Steck-Flynn stated “When hair is used in conjunction with DNA and other evidence it can be a powerful tool in an investigation”. Cary T. Oien also states “we can conclude that microscopic hair comparisons are reliable and are indeed a valid scientific method. If a properly trained hair examiner uses valid procedure, the examiner can achieve correct results”. Therefore, we can determine that hair should continue to be used in a courtroom as a validation for evidence.
